Abstract: K₃[Fe(C₂H₅P₂O₇)₂]·4,5H₂O, and K₃[Fe(C₂H₆P₂O₇)₂(OH)₂]·3H₂O have, been prepared in. solid state and characterized by chemical analysis, Mossbauer spectra, infrared spectra, gravimetric: and differential thermal analysis and conductivity measurement.The two compounds are both high spin complexes. From quadru-pole splitting, the symmetry around Fe atom has been shown by Mossbauer parameters of these complexes as . compared with the values of Fe(Ⅲ)-complexes, The, changes of isomer shifts are dependent on the strength of covalent bond between Fe (Ⅲ) and the ligands.The results of IR spectra and other measurements have also been discussed briefly. A probable stfuctural formula is given for each complex.